Heat removal has become essential for the proper performance of high density microelectronics, optical devices, instrumentation and other devices. One field where heat removal may be especially critical is aerospace. All satellites, space borne vehicles and avionics depend upon their thermal control systems to allow the instruments, communication systems, power systems and other electronic devices to operate within a specified temperature range. In simplest terms, cooling is provided by conductance of thermal energy away from warm sources into radiators or heat exchangers and then dispersed.
In satellite applications, cooling is typically performed by simple conductance from the warm source into a conduction plane, through a mounting interface, into a heat pipe and then into a radiator and radiated into space.
The increasing use of high-performance, space borne instruments, electronics and communication systems result in the need to dissipate much larger thermal loads while meeting demanding weight and size constraints. In addition, tight temperature control is also required for optical alignment needs, lasers, and detectors. Further the drive for miniaturization with micro electro-mechanical systems increases the pressure to develop efficient thermal regulation systems. This creates an environment demanding an efficient thermal control solution. One proposed thermal regulation system is heat pipe systems. Pulsating heat pipes have been produced on a laboratory scale from small diameter bent tubing, as illustrated in FIG. 1.
Pulsating heat pipes are passive thermal control devices, employing a heat source evaporation section and a heat sink condensation section of the pipe to effect a two-phase heat pipe. Pulsating heat pipes have consisted of one or more capillary dimension tubes bent into a curving structure to form parallel or interwoven structures. For example, FIG. 1 shows a device having tube sections 1, having end bends 2. The tube sections are mounted on a plate 3, having mounting holes 4 allowing the plate to be secured onto a fixed location. Plate surface 5 and/or exposed tubes on the end of plate 5 will absorb heat from the heat source, causing evaporation of some of the liquid within the tubes 1 and driving fluid flow. At bends 2, heat is transferred (e.g., by radiation or convection) allowing this part of the device to act as a heat sink. Liquid within the tubes condenses at the heat sink, further driving fluid flow. The vapor “pulses” generated by the heat source and at least partially condense at a heat sink condensation region. The use of a looped structure allows evaporation and condensation at “bend” locations along the length of the pipe, providing greater surface area for heat to be absorbed or radiated.
FIG. 1 is a reproduction of a Kenzan fin pulsating heat pipe. In one example the base plate is 80 mm square and 2 mm thick, with a 450 Watt heat through put capacity and a thermal resistance of 0.089° C./W. The tubing has an interior diameter of 1.2 mm, with the pipe making 500 turns.
Presently pulsating heat pipe devices such as those shown in FIG. 1 have been generally described as separate functioning device uncoupled from the entire system. These laboratory scale pulsating heat pipes have generally been produced from bent tubing. They have demonstrated the performance of a pulsating heat pipe but have a number of drawbacks, including that these devices are difficult to mount effectively to hardware, difficult to manufacture, and relatively fragile.